FIELD OF THE INVENTION
The present invention relates to a catalyst system and a process for combined hydrotreating and hydrocracking operations in a single reactor bed by contacting a hydrocarbonaceous feedstock with hydrogen under hydrocracking conditions in the presence of an appropriate dual function catalyst system. In particular, the catalyst system and process of this invention relate to a combined denitrification and/or desulfurization hydrotreating process and a hydrocracking process wherein the catalyst system exhibits surprising stability and high selectivity for liquid products boiling in the transportation fuels range. The catalyst system can be tailored to provide previously unavailable flexibility with regard to the selection of the hydrocracking catalyst.
The dual function catalyst system of the present invention comprises two randomly intermixed particulate catalysts having distinctly different catalytic functions. The first catalyst is a conventional hydrodenitrification and/or hydrodesulfurization catalyst having substantially no cracking activity. The second catalyst is a conventional zeolitic hydrocracking catalyst. Both catalysts are selected so that they are substantially the same size, that is, the effective diameter for each catalyst particle is substantially the same.
The novel catalyst systems of the present invention have been found to provide surprisingly good selectivity for liquid products and stability against catalyst fouling when used in combined hydrotreating and hydrocracking applications, and can therefore be used to provide a stable catalyst system which offers even heat distribution and reactor control in such applications.